Previous research has linked stress with adverse health change; however, the immunologic mechanisms mediating these changes remain poorly understood. To test whether "stress" was associated with alterations in cell-mediated immunity, we examined the correlations of self-reported life change stress (LCS) and psychiatric symptoms with natural killer cell activity (NKCA) among 114 healthy undergraduate volunteers. Although the bivariate correlation between LCS and NKCA was not significant, subjects reporting few psychologic symptoms in the face of large amounts of LCS ("good copers") had significantly higher NKCA than those experiencing high levels of both symptoms and LCS ("poor copers"). Furthermore, self-reported psychiatric symptoms were found to inversely correlate with NKCA, suggesting that symptoms such as anxiety and depression may negatively affect immunity.